1. Field
The present disclosure relates to a low power consumption type gas sensor and a method for manufacturing the same. More particularly, the present disclosure relates to a low power consumption type gas sensor self-heating and having superior gas sensitivity even when no heat is applied from outside and consuming less power, and a method for manufacturing the same.
2. Description of the Related Art
Gas sensors for detecting toxic gas, explosive gas, environmentally harmful gas, etc. are important in many fields including health care, national defense, counter-terrorism and environment. Researches are consistently ongoing on the gas sensors. In particular, researches are being carried out on the semiconductor gas sensor wherein gas-sensitive metal oxide film is used.
In general, a semiconductor gas sensor comprises a substrate, an electrode formed on the substrate, and a gas-sensing layer formed on the electrode. Recently, efforts are being made to improve gas sensitivity by increasing the specific surface area of the gas-sensing layer of the semiconductor gas sensor. For instance, Korean Patent Publication No. 10-2010-0067972 (Patent document 1) and Korean Patent Publication No. 10-2011-0056694 (Patent document 2) disclose semiconductor gas sensors wherein the gas-sensing layer is formed as nanofibers.
Since the semiconductor gas sensor operates on a simple principle, is compact in volume and costs little, it is expected to be capable of replacing the existing electrochemical or optical gas sensors.
Furthermore, if a semiconductor gas sensor having high sensitivity for the gas to be detected and consuming less power could be manufactured, it may be mounted on a mobile phone or other mobile devices, thereby further enhancing the functionality of the mobile devices.
However, no gas sensor with excellent light transmittance in the visible region without sacrificing performance has been reported as yet. In addition, despite the many advantages over the electrochemical or optical gas sensors, the existing semiconductor gas sensors are not widely used for practical applications because an additional heat source is necessary. That is to say, the existing semiconductor gas sensor has good gas sensitivity only when heat of 200-400° C. is supplied from an external heat source such as a metal heater. Besides, the existing semiconductor gas sensor lacks reliability due to inaccurate change in resistance of the gas-sensitive material because of high contact resistance between the metal of the electrode and the gas-sensing layer. In addition, it consumes a lot of power. For example, power consumption, of a general existing thick-film gas sensor is about 1 mW, and that of a thin-film gas sensor based on microelectromechanical systems (MEMS) is about 10-200 mW.